Waste material, and especially organic waste material, may be decomposed by various micro-organisms. The decomposition process may also be enhanced by the addition of air to the waste material. The end product is a compost material which may be used as a soil nutrient and/or additive in such activities as farming and gardening.
A number of apparatuses and methods have been developed to decompose waste material. U.S. Pat. No. 4,837,153, for example, discloses a composting apparatus that includes a plurality of lances that may be inserted into waste material for introducing air into the waste material. Each of the lances includes a rotatable inner tube, a middle tube, an outer mesh tube, and a plurality of gaskets disposed between the middle and outer tubes to control air flow. With such a configuration, the lances are relatively complex and costly to manufacture. Furthermore, the lances are connected to one or more blowers that provide a relatively high volume of air to the lances such that process costs are significant.
U.S. Pat. No. 5,846,815 discloses a continuous composter with self contained aeration zones so that air is confined to any one zone. An inlet fan and an exhaust fan are provided for each zone, and the inlet fans provide air to the zones through conveyor trays moveably disposed proximate the bottom of the composter. The conveyor trays are also adapted to support waste material thereon for moving the waste material along the composter. Such an arrangement is relatively complex and costly to manufacture. Furthermore, because air is introduced to the waste material near the bottom of the composter, rather than being injected into the waste material, portions of the waste material may experience little or no air flow. Consequently, such portions of the waste material may experience little or no aerobic activity.
U.S. Pat. No. 5,417,736 discloses a method for aerobic composition of organic waste material that involves high flow-rate aeration. The apparatus used in the method includes a bag for receiving the waste material, a plurality of air conduits that penetrate the bag and are adapted to extend into the waste material, and a blower connected to the air conduits for supplying air to the air conduits. The method and apparatus disclosed are undesirable for at least a couple of reasons. First, the method involves introducing a relatively high volume of air into the waste material such that process costs are significant. Second, untreated process air is discharged directly to the atmosphere through vents in the bag.